package com.hqc.util.wx;

import java.util.List;
import java.util.Stack;
import java.util.Vector;

/**
 * See the license below. Obviously, this is not a Javascript credit card number
 * generator. However, The following class is a port of a Javascript credit card
 * number generator.
 *
 * @author robweber
 */
public class RandomCardNumberUtil {
    /*
     * Javascript credit card number generator Copyright (C) 2006-2012 Graham King
     *
     * This program is free software; you can redistribute it and/or modify it
     * under the terms of the GNU General Public License as published by the
     * Free Software Foundation; either version 2 of the License, or (at your
     * option) any later version.
     *
     * This program is distributed in the hope that it will be useful, but
     * WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
     * Public License for more details.
     *
     * You should have received a copy of the GNU General Public License along
     * with this program; if not, write to the Free Software Foundation, Inc.,
     * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
     *
     * www.darkcoding.net
     */

    public static final String[] VISA_PREFIX_LIST = new String[]{"4539",
            "4556", "4916", "4532", "4929", "40240071", "4485", "4716", "4"};

    public static final String[] MASTERCARD_PREFIX_LIST = new String[]{"51",
            "52", "53", "54", "55"};

    public static final String[] AMEX_PREFIX_LIST = new String[]{"34", "37"};

    public static final String[] DISCOVER_PREFIX_LIST = new String[]{"6011"};

    public static final String[] DINERS_PREFIX_LIST = new String[]{"300",
            "301", "302", "303", "36", "38"};

    public static final String[] ENROUTE_PREFIX_LIST = new String[]{"2014",
            "2149"};

    public static final String[] JCB_PREFIX_LIST = new String[]{"35"};

    public static final String[] VOYAGER_PREFIX_LIST = new String[]{"8699"};

    static String strrev(String str) {
        if (str == null)
            return "";
        String revstr = "";
        for (int i = str.length() - 1; i >= 0; i--) {
            revstr += str.charAt(i);
        }

        return revstr;
    }

    /*
     * 'prefix' is the start of the CC number as a string, any number of digits.
     * 'length' is the length of the CC number to generate. Typically 13 or 16
     */
    static String completed_number(String prefix, int length) {

        String ccnumber = prefix;

        // generate digits

        while (ccnumber.length() < (length - 1)) {
            ccnumber += new Double(Math.floor(Math.random() * 10)).intValue();
        }

        // reverse number and convert to int

        String reversedCCnumberString = strrev(ccnumber);

        List<Integer> reversedCCnumberList = new Vector<Integer>();
        for (int i = 0; i < reversedCCnumberString.length(); i++) {
            reversedCCnumberList.add(new Integer(String
                    .valueOf(reversedCCnumberString.charAt(i))));
        }

        // calculate sum

        int sum = 0;
        int pos = 0;

        Integer[] reversedCCnumber = reversedCCnumberList
                .toArray(new Integer[reversedCCnumberList.size()]);
        while (pos < length - 1) {

            int odd = reversedCCnumber[pos] * 2;
            if (odd > 9) {
                odd -= 9;
            }

            sum += odd;

            if (pos != (length - 2)) {
                sum += reversedCCnumber[pos + 1];
            }
            pos += 2;
        }

        // calculate check digit

        int checkdigit = new Double(
                ((Math.floor(sum / 10) + 1) * 10 - sum) % 10).intValue();
        ccnumber += checkdigit;

        return ccnumber;

    }

    public static String[] credit_card_number(String[] prefixList, int length,
                                              int howMany) {

        Stack<String> result = new Stack<String>();
        for (int i = 0; i < howMany; i++) {
            int randomArrayIndex = (int) Math.floor(Math.random()
                    * prefixList.length);
            String ccnumber = prefixList[randomArrayIndex];
            result.push(completed_number(ccnumber, length));
        }

        return result.toArray(new String[result.size()]);
    }

    public static String[] generateMasterCardNumbers(int howMany) {
        return credit_card_number(MASTERCARD_PREFIX_LIST, 16, howMany);
    }

    public static String generateMasterCardNumber() {
        return credit_card_number(MASTERCARD_PREFIX_LIST, 16, 1)[0];
    }

    public static boolean isValidCreditCardNumber(String creditCardNumber) {
        boolean isValid = false;

        try {
            String reversedNumber = new StringBuffer(creditCardNumber)
                    .reverse().toString();
            int mod10Count = 0;
            for (int i = 0; i < reversedNumber.length(); i++) {
                int augend = Integer.parseInt(String.valueOf(reversedNumber
                        .charAt(i)));
                if (((i + 1) % 2) == 0) {
                    String productString = String.valueOf(augend * 2);
                    augend = 0;
                    for (int j = 0; j < productString.length(); j++) {
                        augend += Integer.parseInt(String.valueOf(productString
                                .charAt(j)));
                    }
                }

                mod10Count += augend;
            }

            if ((mod10Count % 10) == 0) {
                isValid = true;
            }
        } catch (NumberFormatException e) {
        }

        return isValid;
    }

    public static String generateCardNum() {
        String cardNum = "";
        int howMany = 1;
        String[] creditcardnumbers = generateMasterCardNumbers(howMany);
        for (int i = 0; i < creditcardnumbers.length; i++) {
            cardNum = creditcardnumbers[i];
        }
        return cardNum;
    }
}
//该代码片段来自于: http://www.sharejs.com/codes/java/7103